CN104453879B - The Forecasting Methodology of pressure before boring - Google Patents
The Forecasting Methodology of pressure before boring Download PDFInfo
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- CN104453879B CN104453879B CN201410645949.7A CN201410645949A CN104453879B CN 104453879 B CN104453879 B CN 104453879B CN 201410645949 A CN201410645949 A CN 201410645949A CN 104453879 B CN104453879 B CN 104453879B
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- 238000000034 method Methods 0.000 title claims abstract description 26
- 230000015572 biosynthetic process Effects 0.000 claims abstract description 47
- 239000011148 porous material Substances 0.000 claims abstract description 45
- 238000005553 drilling Methods 0.000 claims description 13
- 238000012937 correction Methods 0.000 claims description 11
- 230000002706 hydrostatic effect Effects 0.000 claims description 3
- 230000002093 peripheral effect Effects 0.000 claims description 3
- 241001074085 Scophthalmus aquosus Species 0.000 abstract 1
- 238000005755 formation reaction Methods 0.000 description 34
- 239000011435 rock Substances 0.000 description 5
- 239000012530 fluid Substances 0.000 description 3
- 230000002159 abnormal effect Effects 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 1
- 238000005056 compaction Methods 0.000 description 1
- 238000007405 data analysis Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 230000002427 irreversible effect Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000004044 response Effects 0.000 description 1
Classifications
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B49/00—Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B47/00—Survey of boreholes or wells
- E21B47/06—Measuring temperature or pressure
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- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Geology (AREA)
- Mining & Mineral Resources (AREA)
- Physics & Mathematics (AREA)
- Environmental & Geological Engineering (AREA)
- Fluid Mechanics (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Geophysics (AREA)
- Geophysics And Detection Of Objects (AREA)
- Force Measurement Appropriate To Specific Purposes (AREA)
Abstract
The invention discloses before a kind of brill pressure Forecasting Methodology, the Forecasting Methodology includes：A1, speed V that purpose wellblock different depth is obtained by seismic data, and the formation pore pressure coefficient C of corresponding initial predicted is calculated according to speed Vp；A2, the formation pore pressure coefficient C to the initial predictedpIt is modified, to obtain the formation pore pressure coefficient C of purpose wellblockpj.The present invention bores the Forecasting Methodology of front pressure by being modified on the basis of the formation pore pressure coefficient of initial predicted purpose wellblock, so as to the formation pore pressure coefficient of revised purpose wellblock can be made closer to measured value, improves the accuracy of prediction.
Description
Technical Field
The invention relates to a prediction method of formation pore pressure, in particular to a prediction method of pre-drilling pressure.
Background
Drilling data show that overpressure in a sunken stratum of the West lake generally develops, and a well kick phenomenon appears in a part of drilling processes, so that the safety and the drilling efficiency of drilling engineering are seriously influenced. In order to design a reasonable well structure and protect an oil-gas reservoir, an accurate pre-drilling pressure prediction result is particularly important.
Through the research on the rock response characteristics of abnormal pressure, domestic and foreign scholars summarize a plurality of rock elasticity, electrical property and other parameters related to the pore pressure of abnormal formations, overpressure formations are usually expressed as low-layer velocity, high Poisson's ratio, low resistivity and the like, the most common method at present is to predict the pore pressure of the formations by using the characteristics of layer velocity reduction caused by overpressure, but factors influencing the velocity are many, such as lithology, fluid properties in pores and other factors can also cause the change of the velocity, and the traditional method does not take the system into consideration when calculating the pore pressure of the formations, thereby causing the reduction of the prediction precision.
Disclosure of Invention
The invention aims to provide a method for predicting the pressure before drilling, which can improve the accuracy of a prediction result by correcting an initial formation pore pressure coefficient.
In order to achieve the above object, the present invention provides a method for predicting a pre-drill pressure, the method comprising: a1, obtaining acoustic wave velocities V of different depths of a target well area through seismic data, and calculating a corresponding initial predicted formation pore pressure coefficient C according to the acoustic wave velocities Vp(ii) a A2, formation pore pressure coefficient C for the initial predictionpCorrecting to obtain the formation pore pressure coefficient C of the target well zonepj。
Preferably, the step a2 specifically includes: a20, calculating a correction coefficient Pc: according to formula Pc＝M1ln(v)－M2Calculating to obtain PcWherein M is1、M2Respectively representing correction parameters, and fitting by the ratio of the peripheral drilled actual formation pore pressure coefficient to the corresponding predicted value and the speed; a21, calculating the formation pore pressure coefficient C of the target well zonepj: according to formula Cpj＝Pc×CpCalculating to obtain Cpj。
Preferably, M1Has a value range of 0.4-1.2, M2The value range of (A) is 2 to 8.
Preferably, M1Is 1.0437, M2Is 7.6139.
Preferably, the formation pore pressure coefficient C initially predicted in step A1pThe calculating method comprises the following steps: a10, obtaining the vertical effective stress sigma of the target well regionev: according to the original loading curve formula:calculating to obtain sigmaevA, B are empirical coefficients obtained by regression of data from neighboring wells, respectively; alternatively, according to the unloading curve formula: v5000 + A [ sigma ]max(σev/σmax)1/U]BAndcalculating to obtain sigmaevWherein U represents the elastoplasticity coefficient of the mudstone, sigmamaxIndicates the maximum vertical effective stress, i.e. the vertical effective stress at the beginning of the unloading, VmaxExpression and σmaxA corresponding acoustic wave velocity; a11, calculating the initial predicted formation pore pressure Pp0: according to the formula: pp0＝P0－σevCalculating to obtain Pp0Wherein P is0Representing overburden pressure; a12, calculating the initial predicted formation pore pressure coefficient Cp: according to formula Cp＝Pp0/PhCalculating to obtain CpIn which P ishIs hydrostatic pressure.
Preferably, A is in the range of 1-200, B is in the range of 0.1-2, and U is in the range of 2-6.
According to the method for predicting the pre-drilling pressure, the correction coefficient is added on the basis of initially predicting the formation pore pressure coefficient of the target well region, so that the corrected formation pore pressure coefficient of the target well region is closer to an actual measurement value, and the prediction accuracy is improved.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:
FIG. 1 is a flow chart of a method of predicting pre-drill pressure of the present invention;
fig. 2 is a correction coefficient fitting graph.
Detailed Description
The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.
As shown in fig. 1, the method for predicting the pre-drilling pressure of the present invention includes:
step 100: obtaining acoustic wave velocities V of different depths of a target well area through seismic data, and calculating a corresponding initially predicted formation pore pressure coefficient C according to the acoustic wave velocities Vp。
Wherein the initially predicted formation pore pressure coefficient CpThe calculating method comprises the following steps:
step 101: obtaining the vertical effective stress sigma of the target well regionev。
In which the acoustic velocity V (compared to undercompressure) is significantly reduced in overpressured formations where fluid expansion is responsible, Bowers refers to the velocity dip zone, where the high pressure caused by fluid expansion dominates, and the unload curve formula determines its vertical effective stress σevOther formations are determined using the original loading curve formula. In particular toComprises the following steps:
(1) original loading curve formula:
according to the original loading curve formula:calculating to obtain sigmaevWherein A, B are data (V and σ) according to the neighboring well regions respectivelyevWhere σ isevObtained from measured formation pressure or normal compaction segment data) regression.
(2) Unloading curve formula:
according to the unloading curve formula: v5000 + A [ sigma ]max(σev/σmax)1/U]BAndcalculating to obtain sigmaevWherein U represents the elastoplasticity coefficient of the mudstone, sigmamaxIndicates the maximum vertical effective stress, i.e. the vertical effective stress at the beginning of the unloading, VmaxExpression and σmaxThe corresponding acoustic wave velocity.
Wherein V is the main lithology of the rock without much changemaxUsually the speed value at the starting point of the speed fallback area is taken. It is assumed that the rock in the subsidence zone has experienced the same maximum stress state at the same time in the past.
The elastic-plastic coefficient U of the mudstone is 1, which represents non-permanent deformation and is completely elastic, and the unloading curve is superposed with the original loading curve. U ═ infinity indicates complete irreversible deformation and complete plasticity.
Wherein, the value range of A is 1-200, the value range of B is 0.1-2, and the value range of U is 2-6.
Step 102: calculating an initial predicted formation pore pressure Pp0。
According to the formula: pp0＝P0-σevCalculating to obtain Pp0Wherein，P0Representing overburden pressure.
Step 103: calculating an initial predicted formation pore pressure coefficient Cp。
According to formula Cp＝Pp0/PhCalculating to obtain CpIn which P ishIs hydrostatic pressure.
Because the factors influencing the speed have many aspects, the influence of factors other than pressure on the speed is difficult to eliminate. Therefore, in order to further obtain a more accurate formation pore pressure coefficient of the target well region, the step 200 is performed: pore pressure coefficient C of the formation for the initial predictionpCorrecting to obtain the formation pore pressure coefficient C of the target well regionpj。
Wherein, step 200 specifically includes:
step 201: calculating a correction factor Pc。
Since the factors influencing the speed are various, in order to make an accurate pressure prediction by using the layer speed, the influence of the factors except the pressure on the speed should be eliminated theoretically, however, the elimination of the influence of the factors except the pressure on the speed is difficult to realize in actual work. Therefore, on the basis of rock physical experiments and actual data analysis, pressure prediction equations can be respectively established on the assumption that the formation pressure and the longitudinal wave velocity are approximately in a linear relation or a nonlinear relation. This relationship is destroyed when there are other factors affecting the velocity, and in order to reduce the effect of uncertainty factors, a velocity-dependent correction factor (as shown in fig. 2) is introduced into the original pore pressure prediction model to obtain the following prediction equation:
Pc＝M1ln(v)－M2calculating to obtain a correction coefficient Pc, wherein M1、M2The correction parameters are respectively expressed and obtained by the ratio of the peripheral drilled actual formation pore pressure coefficient to the corresponding predicted value and speed fitting (figure 2).
Wherein, depending on the region of investigation, M1Has a value range of 0.4-1.2, M2The value range of (A) is 2 to 8. Preferably, M1Value 1.0437, M2Is 7.6139.
Step 202: calculating the formation pore pressure coefficient C of the target well regionpj。
According to formula Cpj＝Pc×CpCalculating to obtain CpjWherein, CpjIs the corrected pressure coefficient, CpIs the initial predicted pore pressure coefficient.
In this embodiment, the initial predicted formation pore pressure coefficient of the destination well H4 layer is 1.2, the corrected formation pore pressure coefficient is 1.25, and the measured value after drilling is 1.31, which obviously means that the corrected formation pore pressure coefficient is closer to the real value.
According to the method for predicting the pre-drilling pressure, the corrected formation pore pressure coefficient of the target well zone is closer to an actual measurement value by adding the correction coefficient on the basis of the initially predicted formation pore pressure coefficient of the target well zone, and the prediction accuracy is improved.
The preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications can be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.
It should be noted that the various technical features described in the above embodiments can be combined in any suitable manner without contradiction, and the invention is not described in any way for the possible combinations in order to avoid unnecessary repetition.
In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.
Claims (5)
1. A method of predicting pre-drill pressure, the method comprising:
a1, obtaining acoustic wave velocities V of different depths of a target well area through seismic data, and calculating a corresponding initial predicted formation pore pressure coefficient C according to the acoustic wave velocities Vp；
A2, formation pore pressure coefficient C for the initial predictionpCorrecting to obtain the formation pore pressure coefficient C of the target well zonepj；
The step a2 specifically includes:
a20, calculating a correction coefficient Pc：
According to formula Pc＝M1ln(v)－M2Calculating to obtain PcWherein M is1、M2Respectively representing correction parameters, and fitting by the ratio of the peripheral drilled actual formation pore pressure coefficient to the corresponding predicted value and the speed;
a21, calculating the formation pore pressure coefficient C of the target well zonepj：
According to formula Cpj＝Pc×CpCalculating to obtain Cpj。
2. The method of predicting pre-drill pressure of claim 1, wherein M is1Has a value range of 0.4-1.2, M2The value range of (A) is 2 to 8.
3. The method of predicting pre-drill pressure of claim 2, wherein M is1Is 1.0437, M2Is 7.6139.
4. The method of predicting pre-drill pressure as recited in claim 1 wherein the formation pore pressure coefficient C initially predicted in step A1pThe calculating method comprises the following steps:
a10, obtaining the vertical effective stress sigma of the target well regionev：
According to the original loading curve formula:calculating to obtain sigmaevA, B are empirical coefficients obtained by regression of data from neighboring wells, respectively; or,
according to the unloading curve formula: v5000 + A [ sigma ]max(σev/σmax)1/U]BAndcalculating to obtain sigmaevWherein U represents the elastoplasticity coefficient of the mudstone, sigmamaxIndicates the maximum vertical effective stress, i.e. the vertical effective stress at the beginning of the unloading, VmaxExpression and σmaxA corresponding acoustic wave velocity;
a11, calculating the initial predicted formation pore pressure Pp0：
According to the formula: pp0＝P0－σevCalculating to obtain Pp0Wherein P is0Representing overburden pressure;
a12, calculating the initial predicted formation pore pressure coefficient Cp：
According to formula Cp＝Pp0/PhCalculating to obtain CpIn which P ishIs hydrostatic pressure.
5. The method for predicting the pre-drilling pressure according to claim 4, wherein A is in a range of 1-200, B is in a range of 0.1-2, and U is in a range of 2-6.
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Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106401574B (en) * | 2015-07-28 | 2020-06-19 | 中国石油化工股份有限公司 | Method for predicting formation pressure of high-temperature geothermal well before drilling |
| CN107817518B (en) * | 2016-09-12 | 2019-11-01 | 中国石油化工股份有限公司 | A method of improving formation pore pressure precision of prediction |
| CN106970409B (en) * | 2017-05-17 | 2023-08-25 | 成都理工大学 | Gamma absorption dose rate instrument with soil humidity correction function and correction method |
| CN109931055B (en) * | 2019-01-31 | 2020-09-25 | 西北大学 | Fluid Pressure Prediction Method of Deep Basin Complex Origin |
| CN113027427B (en) * | 2019-12-25 | 2024-04-05 | 中石化石油工程技术服务有限公司 | Credibility-containing stratum pressure while-drilling correction method based on Bayesian theory |
| CN113128014B (en) * | 2019-12-30 | 2025-02-07 | 中石化石油工程技术服务有限公司 | A method for predicting pore pressure of formation to be drilled ahead of the drill bit based on grey prediction theory |
| CN114396257B (en) * | 2021-12-31 | 2023-10-31 | 中国石油大学(北京) | Three-dimensional formation pressure prediction method and device based on seismic data |
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Address after: 100010 Beijing, Chaoyangmen, North Street, No. 25, No. Co-patentee after: Shanghai Branch of China National Offshore Oil Corporation Patentee after: China Offshore Oil Group Co., Ltd. Address before: 100010 Beijing City, Dongcheng District Chaoyangmen No. 25 North Street CNOOC building Co-patentee before: Shanghai Branch of China National Offshore Oil Corporation Patentee before: China National Offshore Oil Corporation |